Hyperfine structure and isotope shift of highly excited barium-I states

High-resolution laser-spectroscopy measurements of hyperfine structure and isotope shifts were performed for the 6snd ¹ D ₂ sequence of Ba-I in the regionn=12–24. Stepwise laser excitations of a collimated atomic beam were used. A strong influence on the hyperfine structure is observed at the perturbation atn=14, caused by interaction with the 5d7d configuration. Whereas the isotope shift for the even isotopes stays essentially constant with increasingn, the odd isotopes exhibit a strong change, indicating hyperfine-induced shifts.